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bshell writes "The Verge has a great photo-essay about Tûranor PlanetSolar, the first boat to circle the globe with solar power. 'The 89,000 kg (nearly 100 ton) ship needs a massive solar array to capture enough energy to push itself through the ocean. An impressive 512 square meters (roughly 5,500 square feet) of photovoltaic cells, to be exact, charge the 8.5 tons of lithium-ion batteries that are stored in the ship's two hulls.' The boat is currently in NYC. Among other remarkable facts, the captain (Gérard d'Aboville) is one of those rare individuals who solo-rowed across both the Atlantic and Pacific Oceans, journeys that took 71 and 134 days, respectively. The piece has a lot of detail about control systems and design."

From the sounds of it, he also rowed some other boat across the atlantic and pacific. This is a completely different journey in a different boat. Although I have to wonder, if it's solar powered, why does he have to bring so much weight in batteries? He should be able to travel when there's light, and anchor at night, so as not to stray too far off course. Also, despite the fact the I realize he's probably doing this just to prove he can, there's a million other ways to power a boat, many of which, such as

Ever try to circumnavigate the globe along the equator? That's right, you can't. There's a big difference between 5 weeks sailing as the crow flies across the Atlantic, and sailing all the way around the world.

Of for fuck's sake: lighten up! If you had read the article or any other news related to this project, you would know that the creators of the boat aren't looking to pioneer a new mode of transportation. They all recognize that sailing is a much more effective way of having a "solar-powered" boat. The makers of the Solar Impulse airplane aren't trying to replace commercial aviation, either. These are technology demonstrators, like multi-million dollar concept cars; t

if they're technology demonstrators, but are not meant for the application for which they're demonstrating, then what are they for

Because almost nothing new ever gets done otherwise. Maybe they aren't appropriate for the application today in a one-off fashion, but who can say about tomorrow? And even if the application isn't appropriate, but the integration of the technology is sound, who's to say that it can't be used in a different application? You can get far with thought experiments and designs on

Currents!
If you get in a big barrel, with enough food and water to last 2 months in Gran Canaria someone will find you in 7+ weeks in the Caribbean. Current does the work.
Anyone who's actually crossed the Atlantic knows this. too many ignorant bystanders.
There are simple answers to seemingly complex problems. The first step to solving a problem is understanding....

Lithium ion batteries are stable so long as you don't actively damage them (physically or by over charging, or discharging at an excessive rate). They are only prone to rupture if you physically rupture them (or abuse them by overcharging or discharging at an excessive rate).

I don't even like taking the stairs instead of the elevator in my brother's apartment, lol. So yeah, no gigantic ship towing for me. But yeah, I believe it was in a different boat. Although, rowing once then again and then instead taking a battery-powered solar boat...isn't that like taking the stairs and then being even more daring and taking the elevator? lol.

square hulls don't require ballast, they're stable by nature of the shape. Neither do catamarans or trimarans, they're stable for much the same reason that square hulls are: edge displacement equals or is greater than centre displacement.

An ASCII demonstration:

\/ : single-keel trangular hull. Not very stable because at each point on the hull a different upward pressure acts, resulting in something that requires ballast in the bottom to keep it pointed the right way and/or....Y : triangular hull with sail. Only stable because of the sail (which has ballast in it). Without it, it's about as stable as a log in white water.\_/ : still a triangular hull, this time with a double keel. More stable than the single keel (above), but think of the small rowboats one would use on a lake. Obviously the wider the hull in relation to the length, the more stable it's going to be, but it ain't gonna be capsize-proof. Would still require ballast if it's doing anything other than glass-still laking.|_| : square hull. Very stable because the same upward pressure acts on every point of the hull bottom. Wider=capsize proofing. If you could make a double wardrobe watertight, it would be brilliant as a rescue/evac boat in case of disastrous flooding, because it would hold as much human weight as the total volume of water displaced (40 cubic feet to an inch of the side, for argument's sake, that's 1.13 cubic metres - that's over a ton of water, or a dozen to fifteen full grown adults) and still be rock solid stable.

you're only correct if youre talking about a hull riding smack on the surface and not extending beneath it. ie, you're ignoring CG, displacement, and actual bouyancy dynamics and vastly oversimplifying the problem.

the bouyancy forces acting on a hull dont care if they are acting on the angled side of a V hull or the flat bottom of...well a flat bottomed boat.

the surface area of the horizontal plane of the boat hull where it intersects the waterline is effectively a "flat hull", or the "area upon which the bouyancy forces act", for any boat, regardless of whether the hull is a perfect square or a perfect circle or inverted triangle.

two hulls with different shapes but the same surface area of that plane (and the same displacement and CG are equivealent) will have the same bouyancy forces acting upwards on the hull.

also: catamarans are "not stable for the same reason that square hulls are". that statement alone shows a basic misunderstanding of boat design and simple physics/statics.

a catamaran is stable because if you imagine one side unsupported (such as a wave dropping out frm under it) you have a CG which extended beyond the vessels "base", ie, the remaining outrigger. this causing a natural tipping moment until the unsupported outrigger comes into contact with teh water again.

The boat is interesting, but to me mainly in the sense of where hybrid-electric propulsion can go. PV is a fairly impractical choice for 100% of power, but showing it as possible moves the state of the art further. The lithium batteries would scare the shit out of me though in the middle of the Atlantic. Sure you can have fire suppression and you have at least two independent strings... which is arguably more redundancy than a sailboat with one mast and no engine... But...

I don't completely agree with either parent or GP: hybrid drives are gaining popularity for a number of reasons, and the water viscosity makes regenerating viable despite the prop. FischerPanda used to hae some good material, but I can't find it anymore on their website. Basically, you get a 1kt penalty when running at 8kt if I recall correctly, and you can charge a good size battery bank in a couple hours. You also have a system with plenty of power and don't need an auxiliary engine when cruising.

so you make the front pointy. No biggy. All you have to do is cut the water and move it out of the way as you go. Or (and this is a kickarse idea), gather enough speed so you actually ride above most of the water as a result of upward pressure buildup at the bow (a phenomenon known as hydroplaning - great for boats, not so great for road vehicles). It helps if the front of the vessel is angled to encourage this to happen.

Anyhow, I'm glad you mentioned that. I was going to add something similar. Seeing as you seem to know something about boats...

Another thing that made me wonder is, isn't this a three hulled vessel? Yet, from the summary, the batteries are kept in the "ships two hulls." I am forced to wonder where the third one went but, by doing so, I demonstrate that I've clearly violated the rules of Slashdot and read the article.

It has two hulls which contact the water under normal conditions. The reason the middle hull is nicely shaped like that is so that in rough seas, when water does hit it, it deflects more gently off the sloped sides rather than slamming into a boxlike hull.

Ballast is used to provide righting moment. By putting a large weight on the bottom, if the ship rolls, the weight gets lifted sideways, and gravity generates a moment pushing the weight back to the bottom.

But mass isn't the only way to generate a righting moment. Catamaran and trimaran designs eschew ballast. They generate their righting moment by increasing the lever arm - they put pontoons as far from the axis of roll as possible. As the ship rolls, one pontoon gets dunked further into the water,

Seems to me that 8.5 tonnes of batteries would take more energy to drag across the water than it was worth.

Striking that in a community of self-identified "geeks" and "techies" that the notion of "proof of concept" would be so difficult to grasp.

"Big deal, they walked around on the moon, but they had to wear big heavy protective suits to do it, so clearly, we shouldn't have a space program. And so what that the Mars Rover is tooling around on the surface of Mars. It moves really slowly so we shouldn't do any more Mars exploration until we can bring a Ford Explorer and get around like Jesus intended, with internal combustion engines burning refined oil."

Here's a group that will embrace any new technology, stand in line to buy an Apple iWristwatch, but the mere mention of anything having to do with research into energy from any source besides Big Oil, Big Coal and Big Nukes and they dig in their heels like somebody's trying to take away their binkie.

Sometimes I'm surprised they're not holding out until their laptops can run on a two-stroke engine.

The top speed of a vessel is defined by its length at water line unless the vessel "planes" (flies above the water on a "wing") - water resistance increases with the fourth power of speed and it is futile to try and break this limit.

Sailing ships require one highly trained person and several numbsculls. Generally, numbsculls are cheap. A modern rig can be sailed by a single person most of the time, and only requires extra crew members when the sails need adjusting (probably 30 minutes once or twice a day

Sailing ships can be becalmed for days or even weeks. This is more of a problem the bigger the ship, as the more wind you need to start it moving again. Even at the best of times, their speed is highly variable, depending on wind speed and direction - if it's a head wind then they need to tack, which can significantly reduce their maximum straight-line speed, if it's a run or a reach then they can go faster. This makes them tricky from an economic perspective, where you need to book dock time well in adv

The violent reactions that lithium ion batteries have when exposed to water are all to do with very high electrical currents. Any battery or electricity storage mechanism that has the ability to discharge these high c

I am not entirely sure what you're talking about. Perhaps you goofed and posted this in the wrong spot? I do that but I'm usually pretty wasted at the time.

I suppose now would be the time to say, "It happens to the best of us." I suspect that isn't true however. It is sort of like, well... Have you ever noticed that it is usually a completely retarded idea or vocalization that results in someone saying, "Great minds think alike!" Anyhow, I doubt it happens to the best of us. It happens to me when I'm comple

I am hoping that you know this but I am compelled to respond to your post. I feel like I'm potentially preaching to the choir here but, well, it could be possible that you don't know this. If you don't then, well, I feel sad for you but not in a bad way. The quote is pretty common... The quote is also usually finished with a statement about how the USSR just used a pencil.

The reality is that NASA didn't develop (or pay for the development) of the space pen at all. It was developed by Fisher, at their own expense, and with no guarantee that it would be purchased by NASA for use in space. What had happened was that NASA had paid way too much money for some mechanical pencils and the public found out about the expensive pencils and all hell broke loose. Keep in mind how much we were spending on the space race at the time, be sure to convert those dollars to today's dollars for a true comparison. Americans were well and truly pissed and justifiably so.

What the above link sort of touches on is the trouble with the idea of using a pencil, which is something you hadn't mentioned at all but I'll bring it up in order to be complete. One of the reasons that I understand a pencil is a bad idea (while sort of mentioned in the article they don't go into in at any depth and don't cover this specifically) is that every time you write there are microscopic fragments of graphite that break away. In a weightless environment they can go all over the place and graphite is also a very good conductor of electricity. The various electronics were very sensitive at the time and while most systems had a backup any point of failure was seen as a bad thing. The small bits of graphite could conceivably float away, enter a computer system, and cause a short - which wouldn't necessarily result in a fire but could possibly be a Bad Thing® and *could* potentially cause a fire in and of itself. (I'm not sure how well pencils themselves burn or how much the flammability of the pencil itself was a concern that actually was for NASA to be honest.)

That is, as near as I can remember, how the story was relayed to me by someone who worked on the earlier Apollo missions. The conversation was over more than one beer (and about a lot more than that) so I may have missed something. The linked citation pretty much goes along with the story as he detailed it.

If I may digress a bit... I was not alive for the earliest launches but I do recall watching the first humans on the moon on television. My parents told me the cliché about how I could do that someday but I never really wanted to walk on the moon. It did change me though. It made me interested in the technology and the computers that got them there. I didn't want to walk on the moon but I did want to work one of those giant beeping machines with the interesting dials and gauges on the ground and maybe visit space for a little while just to experience weightlessness but I wouldn't want to stay there for long. Not every little boy wanted to be an astronaut when we grew up, some of us wanted to play with the machines that went beep instead. And, well, that was me. I never did get to play with NASA's beeping machines but I've was in front of a computer for pretty much all of my professional life and still sit in front of one now that I'm retired.

the technology's there, why not use it? Why not use *both*, indeed?As someone else has already pointed out, you don't need to lift the load in water, the water does that: the vessel finds a point where its mass equals the mass of water displaced and there finds a neutral buoyancy. All you need to do then, is push it with enough force to overcome hydrostatic friction and send it on its way. 10% of an oceangoing vessel for fuel is a stupendous amount of deadweight. Most tankers have *tiny* fuel tanks - often

1. It's a proof of concept, a way to develop the technology into something useful.

2. The energy required to produce the batteries would be better compared to the energy required to power a diesel engined boat. You have to compare over the total lifetime of the batteries as well, because once built the fuel is basically free.

I imagine in future we will see large container ships, which are already one of the most efficient ways of moving stuff around, come fitted with solar arrays and maybe kites to provide s

You could use the air currents that solar energy creates naturally to push a boat through the water, by erecting a large semi-rigid surface to catch those currents and transfer energy to the hull. By angling this surface, you could allow the hull to move in a direction different from the air current itself.

If the current happen to disappear for a short time, and that was a problem, you could use a small motor/battery/solar array to keep the boat in motion.

Of course, wind powered boats have been circumnavigating the globe since the 16th century, and can be faster, too. So this is interesting, but not exactly that impressive as a demonstration of eco-friendly sea travel.

Did you RTFA? Despite covering the entire ship with 18% efficient solar panels, it produces a whopping 27 hp and averages only 5 knots. The fastest open-water sailboat [wikipedia.org] can go more than 10x faster.

Wind power is solar power. Why put expensive solar collectors on the boat itself, when you can let the ocean collect the solar energy for free, and siphon that power off of the wind it creates.

Commercial transport ships can't afford to sit around and wait for favourable wins. This technology may not improve enough or scale up well enough to become commercially viable for large-scale use for commercial vessels, but it has a much better chance than all-wind powered (i.e. better than none).

Also, diesel and other fossil fuels are also solar power if you really want to get technical about it.

Add to that: speed doesn't matter to commercial transports nearly as much as reliability. There are a lot more people who are willing to accept shipment in 3 weeks from today than in 2-4 weeks from today. 5 knots is probably a little bit too slow, but 10-15 knots is a very respectable speed for a large cargo ship. It doesn't seem like much, but you cover a lot of distance doing 10 knots 24 hours a day...

Did you RTFA? Despite covering the entire ship with 18% efficient solar panels, it produces a whopping 27 hp and averages only 5 knots. The fastest open-water sailboat [wikipedia.org] can go more than 10x faster.

Large ships like tankers only go about 12 knots. I'll agree that this isn't quite there, and it remains to be seen if it can be scaled up. I think that as scales go up the amount of power should go down relative to size. Otherwise if it takes 8 tons of batteries in a 100 ton ship just imagine what it will take to move a 550kton tanker.

Biggest issue with sails of course is being caught becalmed. People used to die from that...

It may well be easier to integrate into large transport ships though. Something like an oil tanker has a large surface area that could be covered with PV panels and provide extra propulsion to supplement the diesel engines.

Also sails don't provide any electrical energy, which in some applications (e.g. floating laboratory, drone boat) could be very useful.

Why is it that on Slashdot if any new technology doesn't replace all existing ones in every imaginable application for very possible user it must be worth

There have been ships capable of navigating the high seas, 5500 years ago!

So? Circumnavigating is a much harder feat. Glancing at discussion on it, apparently it takes one now about two to ten years to do it now, including careful planning to avoid dangerous storm seasons and human-based perils.

There have been ships capable of navigating the high seas, 5500 years ago!

Er is that the point of view of academics whose closest contact with the ocean is when they take a bath? Yeah I'd like to see one of those ancient vessels in an average storm. I have sailed, and believe me you quickly realize how easy it is to visit the bottom of the ocean.

Just because they didn't, doesn't mean they couldn't.
Actually, it probably does mean that. While there is evidence that ancient peoples were capable of incredibly long trips - the proof of which being the colonization of Pacific islan

Most of the more distant islands were colonised during small ice ages, when it was possible to walk much of the distance and people had to move a lot because food was scarce. There was thought to be a land bridge from South-East Asia to South America well after homo sapiens came along, and getting from Europe to North America via Iceland and Greenland wasn't such a massive journey for a lost Viking ship aiming for the islands around the north of Scotland.

I saw this in the news last week... I didn't think at the time to question to weight of the batteries, but it occurs to me that using a catamaran design is suboptimal. You might as well go with a monohull, and design it around the batteries as ballast.

This has 512 m^2 solar array, incoming sun at directly overhead is roughly 1 kW / m^2, assume solar panel efficiency of 15%. This is a total power of about 76 kW or about 100 HP when the sun is directly overhead. Averaged over a 24 hour day, this is maybe 20-25 HP.
89,000 kg of lithium battery at 200 Wh / kg is 17.8 MWh. This would take 234 hours to charge with the sun directly overhead. That is about 40 days of clear sky charging, assuming you are not running the propeller at the same time. Something is fishy here.
Sounds like he charges in port, then runs to the next port on solar plus battery (otherwise there is no need for this large battery / solar cell ratio). Then he repeats. Is my math wrong, or is this story a bit strange?

85 tons is the displacement of the boat. 11.7 tons is the weight of the battery, so the charging time and capacity are less than you think. Where do these ominous HP come from in your calculation, anyways? How many HPs do the electrical outlets in your house have?

I wonder where the sweet spot is in terms of efficiency. Carrying lots of batteries lets you more consistently provide power to your engines. At night, obviously, but also during cloud cover. But it also makes you a lot heavier. On land, that would mean you'd need to spend a lot more power to move yourself. Maybe not as big of a deal for craft that travel in water?

I'm curious what sort of time one could make with a small(ish) craft with a small(ish) battery that combines solar powered electric engine

We should be investigating the use of wind energy for moving ships. Perhaps there is some way (probably very complicated!) in which we could avoid converting the wind energy to electrical energy before converting it into propulsion. I have a feeling we might be able to create some zero emission ships that way.

the biggest reason sailing fell out of favor is ship size. as freighters get biogger and bigger, the sail needed to move them gets proportionately bigger. can you imagine the sails needed for a modern megatanker? the ballast needed to keep it stable when it heels over? container ships for that matter cant heel, lest the containers fall off (more than already do)

I'm sorry but this is complete nonsense.Francis Chichester sailed around the world under solar power in 1966.
I suspect it was a lot "greener" to build his boat that this.
No wonder Jeremy Clarkson talks about the "green monster"

Ferdinant Magellan did it in 1520. (Wind power is solar power, conveniently converted to a form more amenable to pushing ships.)

No, Magellan only made it as far as the Philippines and then he was killed. It was Juan Sebastian Elcano [wikipedia.org] who completed the voyage.

That's true. And it did take 3 years to finish the voyage. They actually got back in 1522 (those few who made it all the way). However, people sail around the world in sailboats almost routinely now, in under a year.

If you are going to get technical about it where do you think the energy from oil based fuels ultimately came from?

The difference between using battery power (with the batteries charged by solar all on-board) and wind is you can use the batteries even when there is no sunlight. Sailing when there is no wind doesn't last for very long at all.

Wind power will never be efficient enough to enable large transport vessels to use it exclusively. Solar+Batteries is a very real possibility of doing so.

For crying out loud, why such a stupidity - we already had sail ships in the 1600s and 1700s and 1800s that had same size sails as this stillborn, and some of them were really good. Powering this by li-ion and photostatic is an excessive waste of precious resources and should be considered criminal negligence against the future of mankind.

If you want to wage war against anyone wasting precious resources, good luck, this ship is minor leagues compared to others. But I don't think they are trying to replace sails. It's not even claiming to be practical. It's cool that they don't need anything but the sun for powering on-board systems and locomotion. Sometime in the future when battery and photo-voltaic technology improves it will become more practical.

The first horse-less carriages probably seemed wasteful, but look at them now.

And what would you think of a "horseless carriage" that, er, relied on a horse somewhere in the design? Seems like they are over-complicating a very simple, very old concept with modern gadgetry. Just because the propeller was invented does not mean that absolutely the only way to move a ship is via the propeller. What's next, a nuclear powered rowboat?

> energy to build panels is just like ethanol, another energy shell game where the losers are us.

I'll gloss over that solar panels and ethanol do have a net pay off in energy but that isn't the most important factor. With oil, the amount of energy to make the motor+refine+transport (fuel+infrastructure) to site+motor efficiency... consumes the majority of the energy in the fuel to begin with (over 3/4 is lost.) So if the batteries+Solar panels can be made to be more convenient and reduce the risk of po